During the last years miniaturization has become an important task in analytical chemistry. The introduction of micro HPLC and other separation techniques such as the capillary zone electrophoresis (CZE) emphasize this tendency. However, sensitive detection with virtually no dead volume is still difficult, especially in the field of light absorbance detection such as UV/VIS. The need for detectors with small cell volumes has been successfully solved in many instances. UV detectors with cell volumes of only 5-100 nl have been reported and several detectors with a volume of only a few nanoliters are commercially available.
So far, most of these detector cells are based on a simple capillary which is introduced perpendicularly to the light beam of the detector (on-column detection approach).